diff --git a/src/proto/quickfix.pro b/src/proto/quickfix.pro
index c9c3a8c..d58e92f 100644
--- a/src/proto/quickfix.pro
+++ b/src/proto/quickfix.pro
@@ -1,6 +1,7 @@
 /* quickfix.c */
 int qf_init(win_T *wp, char_u *efile, char_u *errorformat, int newlist, char_u *qf_title, char_u *enc);
 void qf_free_all(win_T *wp);
+void check_quickfix_busy(void);
 void copy_loclist_stack(win_T *from, win_T *to);
 void qf_jump(qf_info_T *qi, int dir, int errornr, int forceit);
 void qf_list(exarg_T *eap);